Golgi protein 73 (“GP73”) is a 73-kd resident Golgi membrane protein. GP73 is a type II transmembrane protein with a single N-terminal transmembrane domain and an extensive C-terminal coiled coil domain located on the lumenal surface of the Golgi apparatus. GP73 has been shown to be up-regulated in hepatocytes in viral and non-viral chronic liver disease, which suggests that the protein may be involved in the cellular disease response of hepatocytes. In addition, GP73 levels are higher in patients with liver cancer than in healthy individuals. Fucosylated glycosylation has been found in three quarters of secreted GP73 from hepatocellular carcinoma (HCC) patients. Early studies suggest that GP73 and fucosylated GP73 may be more reliable biomarkers for the early diagnosis of liver disease than current markers such as alpha-fetoprotein (AFP), which has the disadvantage of producing false positive results since AFP is produced under many circumstances, including other liver diseases. In addition, AFP is not present in all patients with HCC. Furthermore, a previously known anti-GP73 antibody, the 14H4-23 monoclonal antibody (provided by Dr. Anand Mehta, Drexel University School of Medicine), is insensitive to the presence or absence of a fucose sugar moiety on the GP73 molecule.
In view of the foregoing, it is an object of the present disclosure to provide anti-GP73 monoclonal antibodies that may be sensitive to the presence or absence of a fucose sugar moiety on the GP73 molecule and bind to the fucosylated form of GP73, or alternatively, are insensitive to the presence or absence of a fucose sugar moiety on the GP73 molecule but have binding affinities sufficient to be used in immunoassays for detecting GP73 and/or fucosylated GP73. This and other objects and advantages, as well as inventive features, will become apparent from the detailed description provided herein.